package interview.huawei.training.p107;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double target = scanner.nextDouble();
        boolean positive = target > 0;
        target = positive ? target : -target;
        double min;
        double max;
        if (target > 1) {
            min = 0;
            max = target;
        } else {
            min = target;
            max = 1;
        }
        while ((max - min) > 0.00001) {
            double mid = min + (max - min) / 2;
            double cube = mid * mid * mid;
            if (cube > target)
                max = mid;
            else if (cube < target)
                min = mid;
        }
        System.out.printf((positive ? "" : "-") + "%.1f\n",max);
    }
}